Submarine sound transmitter



, H. HEcHT ETA;

s uswmmn scum). TRANSMITTER F1193 Feb. 4, 1921 Patented May 2 1925.

I HEINRICH nnonr, or KiEL, AND WALTER nnrinnmmiv AND WILHELM1R UDOLPH or xrrznnnne, NEAR KLEEL, GERMANY,'ASSIG1\ TO3S TO THE rmm SIGNAL ,GESELL- SCHAF'I. M. B. H., KIEL, GERMANY.

'. sunmnnm'n SOUND rnnrrsnrmm Application filed February 4, 1921. Serial m 44am.

(GRANTED UNDER THE PROVISIONS OF THE AGT MARCH 3, 1921, 41 STAI. L, 1313;)

To all whom it may concern: r

Be it known that we, HEINRICH HnoH'r, WALTER HAHNEMANN, and Wmmnmu RUDOLPH, citizens of the German Republic, and residing at Kiel and at Kitzeberg, near Kiel, county of Schleswig-Holstein, State of Prussia, have invented certain new and useful Improvements in Submarine. Sound Transmitters, for which we have filed applications for patent in Germany, on May 3, 1918; Denmark, on May 2, 1919; Sweden, on May 14, 1919; Norway, on May 15, 1919;

Holland, on June 16,1919, and June 23,,

1920; Spain, on July -7, 1920; Belgium, on July'8, 1920; France, on July 8, 1920; Italy, on July'9, 1920; England, on July 10', 1920, and of which the following is a specification. p

This invention relates to. sound producers in h uids, articularly for submarine sound signa in which the exciting force acts on the ember radiating the sound waves by means of a lever. j I V Devices are known particularly in connection with producers of sound in air, in which a lever-is used in order to transfer the exciting force on to adiaphragm, .both for increasing and diminishing the motion amplitudes at the radiator. So faras they cause an increasevin'the motion amplitudes at the radiator they are satisfactory;1 in the case of'air; so far as they diminish t e same they operate for air sound in an entirely unfavourable'sense becaus e with highly compressible media 6 portance to produce; large motion amplitudes. v.

Furthermore, all pure lever systems which are known use a bee i for the lever which is not very favorable or any acoustic pur: poses, inasmuch as the lever is usually pivoted in trunnions or between points; While such pivotal lever arrangement might be permissible in air and might give resultsyalthough of'low eflicienoy, such anal-rangement is absolutely unp'ermissible in sub marine sound receivers or transmitters forwhole in respect to; the frequency of sound the following reasons: In acoustic transmitters 'used in air very large motion amplitudes are being dealt with, so that a slight play in the pivotal jointswould not affect the apparatus to the extent of rendering it useless. In submarine sound transmitters gases) it is above all of im the customary amplitudes are approximately one-hundredth of that inair and amountto only small fractions of a millimeter." Theretached to the lever and the diaphragm,- respectively to the masses m or g in the several modifications, by means, such as soldering orwelding, sotha t a jointless con-- nection is thereby established. .Element 0 attaches lever a to mass 9 or ,m yieldin ly in the direction of vibration but rigi ly at right angles thereto, whereas element 0' attaches lever a to the diaphragm rigidly in the direction of vibration but yieldingly at right angles thereto. We are not aware that 7. the prior art discloses connections. of this. character and forthis purpose in order to increase the efliciency of submarine sound producers.

. It has further been proposed with diephragm transmitters for submarine sound signals to interpose between the points of engagement of the ex'citin force and the diaphragm an acoustic osci lato structure tuned to the frequency of the exciting force, the diaphra'gmbeing connected tothe oscillatory structure at such points'which execute small amplitudes while the exciting force engages the oscillatorystructure at points of large amplitudes. Such devices operate correctly from an acoustic point of view and with [good efficiency, but since the diaphragm equally constitutes an acoustic oscillatory. structure by itself they are thus two-wave devices, i. e. systems-having two 95.

frequencies, while for signal transmlssion only one definite'wave frequency is used.

Finally, in none of the-known devices has it been recognized that the lever .mu'st be so dimensioned that it acts itself as a rigid used. 1 1

Compared with the above the invention consists, above all, in connecting the lever which transmits the exciting force 'to the radiating member between the point of engagement of the exciting force and the radiating member so that the former engages on the long lever arm and the latter on the short lever arm, the lever having bending portions instead of pivots, but being advanused, we mean that the level should constitute a rigid, non-flexible element at the rate of vibrations employed, it being quite thinkable that a lever which is rigid in the above sense within a given range of frequencies will not be so at another frequency or range of frequencies.

As regards the form which the lever itself should assume, much latitude 'is left to the designer. The requirement of rigidity would lead, with massive construction of the lever, in particular with high sound frequencies to structures of rather considerable mass. Itis therefore advantageous to make the structure used as a lever stout in the directionof movement but as narrow as possible in the direction at right angles to the same. F or stiffening in the lateral direction its cross-section should advantageously have the form of a single or double T-beam,

or other suitable shape.

Furthermore, the lever for distributing the engaging forces according to the invention tapers from the point of engagement ofthe large forces acting with small amplitudes towards the points of engagement of J the small forces acting with large amplitudes. In this way-a further very considerable saving in weight is produced.

As a fixed abutment for the lever the casing of the transmitting apparatus itself or any other sufliiently heavy or rigid body located in the vicinity can be used.

If the lever is connected with an elastic oscillatory diaphragm acting as a radiator whose natural frequency agrees with the signal frequency, taking into consideration the co-oscillating lever and water masses, the advantage is obtained that the transmitter developsv a maximum strength of sound in a single frequency, therefore it works with the best possible elficiency.

With continual excitation of the transmitter, the exciter frequency in this case must coincide with the natural frequency of the radiator as the single oscillatory structure present.

It is possible, however, by using levers constructed according to the invention, to

produce also transmitters which can be excited with good efliciency with any suitablev frequency whatever, that is, wh ich permit any desired change of wave. For this it is necessary that the natural frequency of the of wave is to take place. The former is in general to be preferred. The radiator is then advantageously constructed over a definite range as a piston-like rigid plate and provided with a, flexible rim portion.

In the drawings, constructional examples of the invention are represented diagrammatically. In these drawings Fig. 1 is a transmitting arrangement in which the lever is fastened at one side to the transmitter casing.

Fig. 1 is a detail of Fig. 1.

Fig. 2 is a transmitting arrangement in which the lever at its free end terminates in a large mass.

Fig. 3 is a similar arrangement in which the lever co-operates with a piston-like diaphragm.

In Fig. 1 0 represents the lever, b a soundradiator or diaphragm on which the lever or acts. The lever a is connected at one of its ends with the transmitter casing g, at a further place preferably near the previbusly mentioned end with the sound diaphragmr The connections are eflected through strips of metal a and a shaped similar to fish-plates, and which are so disposed that strip 0 yields in the'direction of vibrations but forms a rigid connection at right angles thereto, and strip 0 forms a rigid connection in the direction of vibrations and yields to bending forces at right angles thereto. At the second end of the lever, at the point of engagement of the exciting force in the examples shown in the drawing, the armature d of an electro-magnet is mounted which co-operates with the field magnet e. The latter is excited by a source 'w of alternating current.

Fig. 1 shows a transverse sectlon through the lever along the line n-'n Fig. 1.

In Fig. 2 the casing 9, serving in Fig. 1 as a fixed abutment .for the lever, is replaced by aheavy mass m, which remains stationary'ifi space on movement of the lever on account of its great inertia which prevents it from followin the oscillation The con structional forms of Figs. 1 and 2 are particularly suitable for transmitting a particular sound frequency,which is determined by the natural frequency of the sound diaphragm.

In the constructional example of Fig.3, which serves for transmitting any desired frequencies, in place, of a sound plate of a frequency suitable for the sound pitch, a rigid plate p with a pliable edge portion is used which is moved parallel to itself outwards and inwards by the movement of the lever. In order to avoid detrimental evasive movements of the sound transmitting liquid, i. e. movements -of the water from one part of the diaphragm surface to another, the flexible marginal portion of the diaphragm is advantageously stiffened by ribs 2',

' posed at suitable 2' which permit of flexures or bending only at the inner and outer edges 1' of this marginal portion, or in other words cause the edges 1" to act as pivots.

The excitation of a transmitter accord ing to the invention can of course also take place in another way, for example, by hydraulic or other mechanical impulse 1 in a periodic or continuous form, particularly also by striking; also there is no restriction to the form of lever shown, since any lever of uniform shape be used.

lVe claim:

1. A submarine sound producer comprising a sound radiating member, a lever rigi in tl e direction and Within the range of the excit ng vibrations and a jointless connection between said lever and the sound radiating m'cm )Gl', said connection being rigid in the direction of the vibrations but yielding at right angles thereto, and an exciting device adapted to vibrate the lever; the point of the lever acted upon by the exciting device and the junction point with the sound radiating member being disposed at portions of the lever to cause the first mentioned point to execute larger mot-ions than the junction point with the sound radiating member.

2. A submarine sound producer comprising a sound radiating member, a lever rigi in the direction and within the range of the exciting vibrations and a connection between said lever and the, sound radiating member, said connection being rigid in thedirection of the vibrations but yielding at right angles thereto, a large idle mass yieldingly but jointlessly connected to the lever, and an exciting device adapted to vibrate the lever, both of said yielding connections being disportions of the lever to cause the point of the lever acted upon by the exciting device to execute larger motions than the point of the lever connected to the radiating member.

3. A submarine sound producer comprising a sound radiating member, a lever rigi in the direction and within the range of the exciting vibrations and a connection between said lever and the sound radiating member, said connection being rigid of the vibrations but yielding at right angles thereto, a large idle mass yieldingly but jointlessly connected to the lever, and an exciting device adapted to vibrate the lever,

- both of said yielding connections being disin the direction posed at suitable portions of the lever to cause the point of the lever acted upon by the exciting device to execute larger motions than the point of the lever connected to the radiating member, said large idle mass being embodied in the producer frame surrounding the radiating diaphragm.

4; A submarine sound producer comprising a sound radiating member, a lever in the form of a T shaped element, having its upstanding flange extending in the direction of the sound vibrations so as to make it rigid at the rate of vibration of the sound employed, a jointless connection between said lever and the sound radiating member, said connection bein rigid in the direction of vibration but yiel ing at right angles thereto, and an exciting device adapted to vibrate the lever; the point of the lever acted upon by the exciting deviceand the junction point with the sound radiating member being disposed at suitable portions of the lever to cause the first mentioned point to execute larger motions than the junction point with the sound radiating member. 5. A submarine sound producer comprising a sound radiating member, a leverin the form of a T shaped element, having its upstanding flange extending in the direction of d the sound vibrations so as to make it rigid at the rate of vibration of the sound employed, a jointless connection between said lever and the sound radiating member, said connection bein rigid in the direction of vibrations but y1elding at right angles thereto, and an exciting device adapted to vibrate the lever, the point of the lever acted upon by the exciting device and the junction point with the sound radiating memberbeing disposed at suitable portions of the lever 'to cause the first mentioned point to execute larger motions than the junction point with the sound radiating member, said lever being tapered from said junction point towards the end adjacent to said exciting device.

In testimony whereof we aflix our signatures in presence of two witnesses.

WILHELM RUDOLPH. WALTER HAHNEMANN. HEINRICH HEQHT.

Witnesses:

LEONID ADELM NN, FERDINAND LEHENHELBERGER. 

